Quantitative Variation of Life History Traits in Amphicarpic Peanutgrass (Amphicarpum Purshii) and Its Evolutionary Significance

Abstract

Peanutgrass, Amphicarpum purshii, is a predominantly selling annual that exhibits an amphicarpic reproductive strategy, producing spikelets (and seeds) both above and below the soil surface. Both aerial and subterranean spikelets are self‐fertile, but only the aerial spikelets are chasmogamous and capable of cross‐pollination. This species mostly grows in disturbed areas of the New Jersey Pine Barrens. To examine life history variation, 60 quantitative characters were measured on twelve families raised from seeds collected from the aerial panicles of twelve parents grown in the greenhouse. Only 19 (= 31.7%) of the traits showed significant between‐family phenotypic variation, and the mean percentage of the total variation due to family was 14.9 (N = 60 characters). Percentage biomass allocation and vegetative characters showed the highest narrow‐sense heritabilities. Traits directly relevant to fitness such as subterranean seed set and seed weight of both seed types showed the least genetic variation. This low variation could reflect genetic fixation and/or developmental canalization of those fitness components important to survival in disturbed, early‐successional habitats.

Capitulum characters in a seed heteromorphic plant, Crepis sancta (Asteraceae): variance partitioning and inference for the evolution of dispersal rate

“…Therefore, it appears that the percentage of central achenes, in particular in Crepis sancta , is not only the result of developmental constraints, as suggested by previous studies (Bachmann, 1983; Imbert et al ., 1999), or a plastic trait (Imbert & Ronce, in press), but it is also a trait genetically determined. Equivalent results have been obtained for amphicarpic species (Cheplick & Quinn, 1988), and for other Asteraceae species (Venable & Burquez, 1989; Bachmann & Chambers, 1990). As central achenes in Crepis sancta have a high dispersal ability compared to that of peripheral achenes (Imbert, 1999), the percentage of central achenes represents the potential dispersal rate.…”

“…Yet, few studies have focused on genetic variation in seed morph proportions (see references in Imbert et al . (1999) for Asteraceae species; see also Cheplick & Quinn (1988) for seed heteromorphism in relation to amphicarpy). More scarce are studies of the heritability of seed morph proportions, although estimation of heritability is needed to infer the origin of variation within and among populations (Venable et al ., 1998).…”

Amphicarpic plants: definition, ecology, geographic distribution, systematics, life history, evolution and use in agriculture

“…Plants derived from A < S (Zeide, 1978;Cheplick & Quinn, 1982;Cheplick, 1983) S flowers open earlier than A flowers (Schnee & Waller, 1986;Ruiz de Clavijo, 1995;Ruiz de Clavijo & Jimenez, 1998;Berjano et al, 2014;Choo et al, 2014) A flowers open earlier than S flowers (Kim et al, 2016) Life history Life history trade-offs A flower and seed production are correlated with vegetative mass (Zeide, 1978;Weiss, 1980;Schnee & Waller, 1986 ;Trapp & Hendrix, 1988), while S flower and fruit production are (Schnee & Waller, 1986;Trapp & Hendrix, 1988) or are not correlated (Zeide, 1978;Weiss, 1980) Quantitative genetics of life-history traits Seed set and seed mass of both seed types had low quantitative genetic variation relative to other traits (Cheplick & Quinn, 1988a;Cheplick, 1994) Dormancy and germination Degree (depth) of dormancy A > S (Koller & Roth, 1964;Alinoglu & Durlu, 1970;McNamara & Quinn, 1977;Walker & Evenson, 1985b;Schnee & Waller, 1986;Trapp & Hendrix, 1988;Ruiz de Clavijo, 1995;Ruiz de Clavijo & Jimenez, 1998;Choo et al, 2014Choo et al, , 2015Zhang et al, 2015) A < S (Evenari et al, 1977) Germination and viability response to storage Germination of A and S decreased with dry storage in Amphicarpum amphicarpon (McNamara & Quinn, 1977) Germination of A increased with dry storage, whereas S lost viability (Zhang et al, 2015) Germination of water-permeable seeds Scarification of seed coat increased germination of A more than i...…”

“…Although selfing is an important component of the breeding system of many amphicarpic species, considerable phenotypic variability in quantitative traits exists in populations in which occasional outcrossing occurs and/or individuals are phenotypically plastic (Cheplick & Quinn, 1986, 1988a. In 10 maternal families (i.e.…”

“…Some components of the amphicarpic reproductive strategy show significant quantitative genetic variation among families (Cheplick & Quinn, 1986), but these are not the traits most closely allied to fitness (Cheplick & Quinn, 1988a). Low variation in fitness-related traits could reflect that genetic fixation and/or developmental canalization has occurred for some traits such as those related to subterranean seed production.…”